+# Copyright (C) 2014-2016 all contributors <meta@public-inbox.org>
+# License: AGPL-3.0+ <https://www.gnu.org/licenses/agpl-3.0.txt>
+
+# two-step linkification.
+# intended usage is in the following order:
+#
+# linkify_1
+# <escape unsafe chars for HTML>
+# linkify_2
+#
+# Maybe this could be done more efficiently...
+package PublicInbox::Linkify;
+use strict;
+use warnings;
+use Digest::SHA qw/sha1_hex/;
+
+my $SALT = rand;
+my $LINK_RE = qr!\b((?:ftp|https?|nntp)://
+ [\@:\w\.-]+/
+ ?[\@\w\+\&\?\.\%\;/#=-]*)!x;
+
+sub new { bless {}, shift }
+
+sub linkify_1 {
+ my ($self, $s) = @_;
+ $s =~ s!$LINK_RE!
+ my $url = $1;
+ # salt this, as this could be exploited to show
+ # links in the HTML which don't show up in the raw mail.
+ my $key = sha1_hex($url . $SALT);
+
+ # only escape ampersands, others do not match LINK_RE
+ $url =~ s/&/&/g;
+ $self->{$key} = $url;
+ 'PI-LINK-'. $key;
+ !ge;
+ $s;
+}
+
+sub linkify_2 {
+ my ($self, $s) = @_;
+
+ # Added "PI-LINK-" prefix to avoid false-positives on git commits
+ $s =~ s!\bPI-LINK-([a-f0-9]{40})\b!
+ my $key = $1;
+ my $url = $self->{$key};
+ if (defined $url) {
+ "<a\nhref=\"$url\">$url</a>";
+ } else {
+ # false positive or somebody tried to mess with us
+ $key;
+ }
+ !ge;
+ $s;
+}
+
+1;